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SHIPS: Billfish-class Diesel Powered Attack Submarines
. - - . . . . . . . '~ ''Billfish-class Diesel Powered Attack Submarines ~' ---- . ''Tench-class submarines were a type of submarine built for the United States Navy (USN) between 1944 and 1951. They were an evolutionary improvement over the Gato and Balao classes, only about 35 to 40 tons larger, but more strongly built and with a slightly improved internal layout. One of the ballast tanks was converted to carry fuel, increasing range from 11,000 nautical miles (20,000 km) to 16,000 nautical miles (30,000 km). This improvement was also made on some boats of the previous two classes. Further improvements were made beginning with SS-435, which are sometimes referred to as the Corsair class. Initial plans called for 84 to be built, but 55 were cancelled in 1944 and 1945 when it became apparent that they would not be needed to defeat Japan. The as-built diesel-electric propulsion layout was the same as the last few Balao-class, with four Fairbanks-Morse or General Motors Cleveland Division two-stroke diesel engines supplying two low-speed double-armature direct-drive electric motors to drive two shafts. All except Corsair received the Fairbanks-Morse 38D 8-1/8 engine with 10 cylinders; Corsair had GM 16-278A engines. The direct-drive electric motors were much quieter than the reduction gear arrangement of previous classes, and they made the drive train much more reliable due to the fact that the gearing was an element prone to shock damage from depth charges. Two 126-cell Sargo-type lead-acid batteries provided submerged power to the electric motors. A design weakness of earlier classes solved by the Tench re-design were the ballast tank vent riser pipes that passed through the interior of the boat in the forward and after torpedo rooms. These pipes allowed #1 and #7 Main Ballast Tanks (MBT) (located in the single hull sections of the boat) to vent air during diving and allowing water to flood into them from below. The tops of these tanks formed the walking deck in the interior of both rooms and thus the normal location of the vent valves (the top of the tank) could not be used. The riser pipes allowed the tanks to vent but when the tanks were full these pipes contained water at full submergence pressure inside the torpedo rooms. If these pipes ruptured during depth charge attack, catastrophic flooding would occur. Solving this problem initially proved quite difficult, but ultimately required the complete rearrangement of the ballast tanks. #1 MBT was moved to a location forward of the end of the pressure hull, thus allowing it to vent directly into the superstructure like the rest of the MBT's. This move eliminated the riser pipes completely. #7 MBT, after stability and buoyancy calculations were run was found to be redundant and was converted to a variable fuel oil tank as mentioned above. These changes forced the rearrangement of the associated piping runs and the location of many of the other tanks. Remarkably, these changes resulted in a boat that was visually almost indistinguishable from the earlier Balao-class, with the exception of a sharper angle (or knuckle) at the lower corner of the bow (only visible when the boat was drydocked). A side benefit of the tank rearrangement was that these boats could carry four additional torpedoes in the forward torpedo room, for a total of 28. This was a change that had been asked for by submarine crews much earlier, but could not be accommodated in the earlier designs due to the lack of space in the torpedo rooms. Many targets in the Pacific War were sampans or otherwise not worth a torpedo, so the deck gun was an important weapon. Due to war experience, most Tench-class were armed with a 5 inch (127 mm)/25 caliber gun, and some boats had two of these. Additional anti-aircraft guns included single 40mm Bofors and twin 20mm Oerlikon mounts, usually one of each. With one exception, these boats were all built at government owned shipyards; Portsmouth Naval Shipyard and Boston Navy Yard. Two boats, Wahoo and an unnamed boat designated SS-517 were laid down at Mare Island Navy Yard but canceled and broken up prior to completion. With the end of the war obviously near and due to a huge construction backlog of Balao-class boats, the Electric Boat Company was only awarded contracts for three Tench-class boats, only one of which, Corsair, was completed. Electric Boat's follow on yard, the Manitowoc Shipbuilding Company of Manitowoc, Wisconsin worked through its contracts for Balaos and were not awarded any Tench contracts. The Cramp Shipbuilding Company of Philadelphia, struggling with workforce problems and supply issues with its Balaos, was also not awarded any contracts. Ten of the 29 Tench-class submarines were completed in time to conduct war patrols in World War II, entering service beginning in late 1944. They finished what the previous classes had largely accomplished: the near-destruction of the Japanese merchant fleet. Another significant contribution was the rescue of downed aviators near Okinawa and Japan. Two additional boats (Cutlass and Diablo) entered Japanese waters on their first war patrols immediately after the 13 August 1945 cease-fire. Construction on the last four of the class was suspended, and they were completed 1948-1951. Postwar, 24 of the 29 Tenches were modernized under the Fleet Snorkel and Greater Underwater Propulsion Power (GUPPY) programs, with most continuing in US service into the early 1970s. Fourteen were transferred to foreign navies for years of additional service, and the former USS Cutlass (SS-478) remains active in Taiwan's Republic of China Navy as Hai Shih. At the end of World War II, the US submarine force found itself in an awkward position. The 29 Tench-class submarines, designed to fight an enemy that no longer existed, were obsolescent despite the fact they were only one to three years old. The German Type XXI U-boat, with a large battery capacity, streamlining to maximize underwater speed, and a snorkel, was the submarine of the immediate future. The Greater Underwater Propulsion Power Program (GUPPY) conversion program was developed to give some Balao- and Tench-class submarines similar capabilities to the Type XXI. When the cost of upgrading numerous submarines to GUPPY standard became apparent, the austere “Fleet Snorkel” conversion was developed to add snorkels and partial streamlining to some boats. A total of 16 Tench-class submarines were converted to one of the GUPPY configurations, with 8 additional boats receiving Fleet Snorkel modifications. USS Diablo, one of the Fleet Snorkel boats, was converted immediately prior to transfer to Pakistan. Most of the converted submarines were active into the early 1970s, when many were transferred to foreign navies for further service and others were decommissioned and remained in reserve stocks for decades. Although there was some variation in the GUPPY conversion programs, generally the original two Sargo batteries were replaced by four more compact Guppy (GUPPY I and II only) or Sargo II batteries via significant re-utilization of below-deck space, usually including removal of auxiliary diesels. All of these battery designs were of the lead-acid type. This increased the total number of battery cells from 252 to 504; the downside was the compact batteries had to be replaced every 18 months instead of every 5 years. The Sargo II battery was developed as a lower-cost alternative to the expensive Guppy battery. All GUPPYs received a snorkel, with a streamlined sail and bow. Also, the electric motors were upgraded to the direct drive double-armature type, along with modernized electrical and air conditioning systems. All Tench-class GUPPYs received sonar, fire control, and Electronic Support Measures (ESM) upgrades. The Fleet Snorkel program was much more austere than the GUPPY modernizations, but is included here as it occurred during the GUPPY era. The GUPPY and Fleet Snorkel programs are listed in chronological order: GUPPY I, GUPPY II, GUPPY IA, Fleet Snorkel, GUPPY IIA, GUPPY IB, and GUPPY III. - GUPPY I Two Tench-class boats, Odax and Pomodon, were converted as prototypes for the GUPPY program in 1947. They proved very successful, though not initially fitted with snorkels. Pomodon achieved 17.9 knots submerged on trials, though even the increased battery capacity only allowed one hour of operation at that speed. However, banking and depth control problems resulting from the high speed were noted and eventually compensated for. An advantage of streamlining was that active sonar detection range against a GUPPY was reduced by about 10%, and the higher submerged speed also severely impacted anti-submarine warfare efforts. - GUPPY II This was the first production GUPPY conversion, with most conversions occurring in 1947-49. Ten Tench-class boats received GUPPY II upgrades, including Odax and Pomodon in 1951, the two GUPPY I prototypes. This was the only production conversion with Guppy batteries. - GUPPY IA This was developed as a more cost-effective alternative to GUPPY II. Tench was converted in 1951. The less expensive Sargo II battery was introduced, along with other cost-saving measures. - Fleet Snorkel The Fleet Snorkel program was developed as an austere, cost-effective alternative to full GUPPY conversions, with significantly less improvement in submerged performance. Eight Tench-class boats received this upgrade, one immediately prior to foreign transfer. Most Fleet Snorkel conversions occurred 1951-52. Notably, the original pair of Sargo batteries was not upgraded. Each boat received a streamlined sail with a snorkel, along with upgraded sonar, air conditioning, and ESM. The original bow was left in place, except on three boats that received additional upper bow sonar. A few boats initially retained a 5”/25 deck gun, but this was removed in the early 1950s. - GUPPY IIA This was generally similar to GUPPY IA, except one of the forward diesel engines was removed to relieve machinery overcrowding. Four Tench-class boats received GUPPY IIA upgrades in 1952-54. - GUPPY IB This was developed as an austere upgrade for two Gato-class and two Balao-class boats prior to transfer to foreign navies in 1953-55. They lacked the sonar and electronics upgrades of other GUPPY conversions. - GUPPY III Nine submarines, three of them Tenches, were upgraded from GUPPY II to GUPPY III in 1959-63 as part of the Fleet Rehabilitation and Modernization II (FRAM II) program. All except the Balao-class Tiru, the pilot conversion, were lengthened by 15 feet in the forward part of the control room to provide a new sonar space, berthing, electronics space, and storerooms. Tiru was lengthened only 12.5 feet, and both forward diesel engines were removed. The other GUPPY IIIs retained all four engines. A taller “Northern” sail was included for improved surfaced operations in rough seas; this was also backfitted to some other GUPPY and Fleet Snorkel boats. The BQG-4 Passive Underwater Fire Control Feasibility Study (PUFFS) sonar system, with three tall domes topside, was fitted. Additionally, fire control upgrades allowed the Mark-45 nuclear torpedo to be used. Radar Picket Tenches: The advent of the Kamikaze demonstrated the need for a long range radar umbrella around the fleet. Radar picket destroyers and destroyer escorts were put into service, but they proved vulnerable in this role as they could be attacked as well, leaving the fleet blind. A submarine, though, could dive and escape aerial attack. Ten fleet submarines were converted for this role 1946-53 and redesignated SSR as radar picket submarines. Three Tench-class boats (Tigrone, Requin, and Spinax) were among those converted; the latter two prototyped the concept in 1946. Eventually, the radar pickets were lengthened by 24 feet to provide additional space for an air control center and had powerful air search and height finding radars installed, with the after torpedo room converted into an electronics space with torpedoes and tubes removed. They also received a streamlined sail in place of the traditional conning tower fairwater. The most extensive SSR conversion was the "Migraine III" configuration. Unfortunately, the SSRs proved only moderately successful, as the radars themselves proved troublesome and somewhat unreliable, and the boats' surface speed was insufficient to protect a fast-moving carrier group. The radars were removed and the boats reverted to general purpose submarines after 1959. -- Islands 340' long rebuilds modern batteries and turbocharged diesels . . . ---- 'Specifications:' . -- 340' long 21" - 4fwd / 2rwd 12.75" - 2fwd / 2 rwd -- torpedo-tube launched Harpoons -- torpedo-tube launched Tomahawks -- torpedo-tube launched Anti-Aircraft Missiles . . . ---- 'Vessels of the ''Billfish-class: . ~ six vessels in the Billfish-class ~ . :::::::: -- ''SSS Billfish'' (SS-_), 4th Fleet, :::::::: -- ''SSS Spearfish'' (SS-_), 4th Fleet, :::::::: -- ''SSS Sailfish'' (SS-_), Reserve, :::::::: -- ''SSS Blue Marlin'' (SS-_), Reserve, :::::::: -- ''SSS Swordfish'' (SS-_), Reserve, :::::::: -- ''SSS Black Marlin'' (SS-_), Reserve, . . . ---- '''Gallery: . - Billfish submarine.jpg Billfish koc28.jpg Billfish E8251.JPG - . . . ---- 'Notes:' . . . . . ---- . . . . . Category:NAVY Category:~ SHIPS ~ Category:Submarines